Fiber Composite Acoustic Damping Material

ABSTRACT

A damping material ( 11 ) in accordance with the invention consists of a ground material that is composed of fibers that are in loose connection with each other. For example, the fibers are minimally interlooped with each other or also glued to each other. This ground material is condensed in some areas in that the fibers are reoriented or interlooped with each other to a greater degree or glued to each other. Consequently, zones ( 17 ) and ( 18 ) of different densities are formed, thus making it possible to increase and adjust, as desired, the sound-damping effect of the damping material.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority of European PatentApplication No. 10 002 801.8, filed Mar. 17, 2010, the subject matter ofwhich, in its entirety, is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to an acoustic damping or absorbing material inthe manner of a body consisting of fibers. In particular, the inventionrelates to such a spatially configured, i.e., not simply planar, dampingor absorbing material.

Acoustic damping materials consisting of the most diverse materials suchas mineral wool, glass wool or natural or synthetic fibers have beenknown. In each case, the damping material is to absorb sound energy,i.e., the sound waves are to be attenuated in that the vibration energyof the sound waves is converted by friction into thermal energy. Indoing so, the formation of resonances and the formation of standingwaves is to be prevented.

Fiber materials with non-ordered fibers may display a high acousticdamping effect. In doing so, it is possible—in principle—to design thefelt bodies so as to be relatively variable, as has been known fromdocument EP 2 034 072 A1. This publication deals with a hygiene articlesuch as, for example, sanitary materials. In order to produce suchmaterials, a non-woven fibrous web is needled along strip-shaped areaswith different strengths, so that elongated parallel-oriented zonesdisplaying a higher fiber density are achieved in the material. Theextent to which such a material can be employed for a use other than inthe medical and nursing fields is open.

It is the object of the invention to provide an acoustic dampingmaterial displaying improved efficacy.

SUMMARY OF THE INVENTION

The damping material in accordance with the invention forms a randomfiber non-woven body, i.e., a body consisting of non-ordered fibers. Inthis body, the fibers may be also be arranged parallel to each other inzones. The fibers may be interlooped, in which case the degree ofinterlooping may be different in at least two different zones. Therandom-fiber non-woven body may be produced, for example, in that aloose fibrous web or non-woven (for example of polyester) is condensedby mechanical or also thermal action in specified zones. In doing so, anacoustic damping material displaying spatially varying densities isproduced. In this case, the invention offers a means to produce thisdamping material in a cost-favorable manner.

The acoustic damping material can be provided in the form of a mat. Themat may be made of glass fiber wool or of mineral wool or also of othermaterials, for example. The fibers of the mat in the fibrous web arepreferably arranged next to each other, loosely but still holdingtogether. This can be achieved in that the fibers are interlooped witheach other in such a manner that at least a loose cohesion of the matexists. The fibers may be aligned parallel or may be arranged so as tobe crossed superimposed in layers by means of a cross-laying process.

For example, the fibrous web may first be made available by usingcarding methods or spunbonding processes, these being known per se. Dueto a zone-wise condensation, the loose fibrous web is converted into thedesired state in that zones are created, wherein the degree of fiberinterlooping is greater compared with the remaining body or theremaining mat. Increased fiber interlooping may be achieved bymechanical needling, e.g., with the use of felting needles, bycondensing with water jets or similar techniques. Alternatively, localcondensing may be achieved, for example by thermal compression. Bycondensing the fiber body, the condensed zones become more compact,whereby more interlooped fibers are counted by unit of volume than inthe non-condensed material.

The acoustic damping material may be provided in the form ofrandom-fiber non-woven bodies displaying defined geometric shape or alsoin the form of mats that are cut to the desired size and dimensionsprior to use. It is characteristic of the damping material that at leasttwo, but preferably more, zones displaying at least two degrees of fiberinterlooping do exist.

The zones displaying different degrees of fiber interlooping, preferablyalso have different fiber densities. As a result of this, zones ofdifferent pore volume and different acoustic hardness are formed in thedamping material, so that a strong acoustic damping effect can beachieved.

The zones displaying differently strong fiber interlooping may bearranged in a regular or preferably irregular pattern, as a result ofwhich a broad-spectrum acoustic damping effect can be achieved.

The damping material in accordance with the invention may be produced ofuniform fibers or also of different fibers, for example, of fibershaving different lengths and/or thicknesses, of fibers that consist of auniform material or also of fibers that consist of different fibers,i.e., fiber mixtures. If necessary, fibers having different dimensionsor consisting of different materials may also be concentrated indifferent zones so as to also form zones of different materials inaddition to the zone-specific different degrees of fiber interlooping.

Preferably, the fibers in zones of minimal fiber interlooping arepredominantly oriented in one plane (or in crossed position), wherebythe fibers in the plane may be selectively oriented in paralleldirection or also in different directions, i.e., they cross one or moretimes, but interloop minimally. If the damping material is provided inthe form of a mat, the fibers—in particular in zones of minimal fiberinterlooping—are preferably predominantly in the plane of this mat. Inzones of more fiber interlooping, the fibers—at least preferably—areoriented in an increased proportion in a direction perpendicular to thisplane. As a result of this, condensed zones are formed that impart themat or the other fiber body with a particular mechanical stability and,specifically, with cohesion.

The zones of increased fiber interlooping may be arranged as regularlyor irregularly formed islands in the damping material. Preferably, theyhave the form of strip-shaped—again preferably straight—regions that,for example, may extend in transverse direction of the mat and/or inlongitudinal direction of the mat. Furthermore, they may extend inoblique directions, for example extend diagonally. Preferably, thecondensed zones extend through the entire mat thickness, i.e., from theupper side to the underside of said mat.

Considering a particularly advantageous embodiment, the dampingmaterials comprises at least two layers, wherein zones with differentdegrees of fiber interlooping are provided, in which case these twozones may be arranged differently in the two layers, for example, not ina registered manner. It is possible to provide in these layers condensedzones, i.e., zones with a greater degree of fiber interlooping, saidzones being connected to the respectively other layer. For example, thecondensed zones in these layers may be produced by needling, bywater-jet condensing or the like. A fiber body or a corresponding matcan be produced as a layer. As previously described, such a layer isproduced, for example, by zone-wise compacting the fiber body. Aftersuperimposing two or more such layers, they, in turn, may experiencecompacting in some areas, in which case the degree of fiber interloopingincreases at certain points or in zones (regions) and, in doing so, aconnection is also established between the layers.

Hereinafter, exemplary embodiments of the invention are explained. Theseexemplary embodiments as well as the corresponding drawings andsubordinate claims show additional details of advantageous embodimentsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective schematic representation of a damping materialwith interspersed zones of increased fiber interloping.

FIG. 2 is a schematic perspective principle representation of a devicefor the production of a damping material in accordance with FIG. 1.

FIG. 3 is a perspective principle representation of a damping materialwith local condensed zones.

FIG. 4 is a perspective principle representation of a modifiedembodiment of an inventive damping material with strip-like condensedzones and interstices.

FIG. 5 is a perspective principle representation of another exemplaryembodiment of an inventive damping material consisting of a multi-layerassembly and strip-shaped condensed zones.

FIG. 6 is a perspective principle representation of a modifiedembodiment of a damping material consisting of a multi-layer assembly.

FIG. 7 is a principle representation of a potential production processfor a damping material in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a random-fiber non-woven body 10 that consists of anacoustic damping material 11 and, may be used, for example, for soundabsorption or for sound damping in rooms, in or on room ceilings orwalls, in loudspeaker boxes or other acoustic devices. The random-fibernon-woven body 10 is represented here as a flat, parallel-epipedal body.However, said body may also have a shape that is suitable for therespective purpose of use. In the present exemplary example, therandom-fiber non-woven body 10 depicted as a section of a preferablycontinuously produced mat 12, as shown in FIG. 2.

The damping material 11 is made of an immeasurably large number ofindividual fibers 13, 14, 15, 16 that, for example, may consist of oneuniform material or also of different materials. The fibers 13 through16, as well as the remaining fibers indicated in FIG. 1, said fibers notbeing specifically referenced, may consist in full or in part of glass,ceramic, wool, cellulose, synthetic material, one or more elastomers,one or more polymers or the like. The fibers may consist of only one ofthese materials. However, it is also possible to have a homogeneous orinhomogeneous mixture of fibers that consist of different such mentionedmaterials.

At least some of the fibers 13 through 16 may consist of a metal or of anon-metallic material that may also be metallized. The fibers 13 through16 may have uniform diameters, cross-sections and lengths or alsodifferent diameters and/or or different cross-sections and/or differentlengths.

The fibers 13 through 16 form a fiber web, wherein they are positionednext to each other in a loose but cohesive arrangement. In doing so,different zones may be distinguished in the random-fiber non-woven body10. The fibers 13, 14 are in a loose zone 17 with minimal fiberinterlooping, whereas the fibers 15, 16 are located in a compacted, morecondensed zone 18 with an increased degree of fiber interlooping. Forexample, the zone 17 is formed by the afore-mentioned loose fiber web,whereas the zone 18 represents a compacted zone. Preferably, severalzones with increased fiber interlooping exist in the random-fibernon-woven body 10, for example the zone 18, whereby these differentzones may be formed and/or arranged regularly or irregularly. They mayextend over the entire height of the fiber body 10 (vertically inFIG. 1) or the mat 12.

In the zone 17, the fibers 13, 14 are predominantly arranged in a planethat is essentially parallel to the upper side 19 or the underside 20 ofthe random-fiber non-woven body 10, whereby the fibers 13, 14 arepreferably oriented essentially parallel and in mat longitudinaldirection 21, i.e., with respect to FIG. 2. The fibers 13, 14, as wellas any additional fibers oriented in mat longitudinal direction havebeen joined, for example, in a combing process, by carding a natural orsynthetic fiber to produce a loose non-woven web with parallelizedfibers. In order to produce the fiber body 10 in accordance with FIG. 1,the thusly obtained mat 12 is passed through a processing station 22,said station comprising one or more members 23, 24 that act permanentlyor at selected times on the mat 12 located or passing underneath, inorder to effect a local increased interlooping of the fibers such as,for example the fibers 15, 16, and thus produce a zone 18 with increasedfiber interlooping, respectively. The members 23, 24 may act on the mat12 in a mechanical or non-mechanical manner. In particular, consideringsynthetic fibers, said members may be heat sources, radiation sources oralso only members that dispense jets of organic or inorganic fluids suchas, for example, water. Alternatively, the members 23, 24 may alsocomprise mechanical tools such as felting needles or the like, thesebeing used to treat the mat 12.

For further explanation of the damping material 11 in accordance withthe invention, reference is made to FIG. 3. Again, this damping materialis initially a mat 12, wherein the fibers 13, 14 are largelyparallelized in a loose fiber assembly or also oriented in a crossedmanner essentially parallel to the upper side 19. In the zone 18, saidzone having been created, for example, by local condensing of the mat 12with water jets, the fibers 25, 26 have been reoriented out of thehorizontal orientation into an approximately perpendicular orientationrelative to the upper side 19. Consequently, a greater degree ofinterlooping of the fibers among each other occurs in the zones 18 thanin the remaining zone 17. At the same time, this increased interlooping,as has been created by water-jet condensing for example, is accompaniedby a compacting effect. FIGS. 3 and 4 show how, due to the treatmentprocess, the fibers have been locally reoriented in the zones 18 out oftheir normal orientation in their predominantly horizontal position intoan oblique or perpendicular position, whereby, at the same time, thematerial has been condensed. The reorientation of the fibers 25, 26 outof the horizontal direction (parallel to the upper side 19) into thevertical direction, at the same time, means a compacting of the fibermaterial at the affected location or in the zone 18. The upper side 19and/or the underside 20 may have respectively one indentation in thecondensed zone 18.

Inasmuch as the mat 12 is zone-wise condensed at certain locations andnot condensed at other locations, a varying density structure is formedacross the spatial segments. For example, outside the condensed zones18, it is possible for (hollow spaces) interstices 27 displayingextremely low density, i.e., low proportion of fibers per unit ofvolume, to form, the fiber density in said interstices being lower thanthe density in the remaining fiber web of the mat 12. Such interstices27 may be irregular and be approximately lentil-shaped, for example.Their form and arrangement depend on the form and arrangement of thecondensed zones 18.

The random-fiber non-woven body 10 in accordance with FIG. 1 or FIG. 3exhibits good sound damping properties. It also exhibits a high pore andair volume. Sound waves impinging on the damping material 11 penetratethe damping material 11 and are absorbed there, i.e., ultimatelyconverted into heat. This effect is supported by the preferablyirregular arrangement of the zones 18 that suppress the formation ofstanding waves and may achieve an additional wave extinction in a largefrequency spectrum due to interference. Such interference may occurwithin the damping material 11 as well as outside said damping material.As is shown by FIG. 3, the condensed zones 18 may also be formed byindentations that are preferably irregularly arranged on the surface ofthe material, said indentations reflecting a certain percentage of theimpinging sound energy and, together, contributing to the extinguishinginterference.

The damping material 11 may be designed in various ways. While the zones18 in the embodiments described so far are formed by local islands, forexample having a rectangular, square, circular or another contour, theymay also be strip-shaped, as shown by FIG. 4. The strips may haveconsistent or changing width. The strips may have one uniform width orthey may have different widths.

The damping material 11 as in FIG. 4 has several zones 18, 28, 29 withincreased fiber interlooping, three of these being shown. These zonesextend at a distance parallel to each other along the transversedirection of the mat 12 (at a right angle to the mat longitudinaldirection 21) in FIG. 2 for example, or also parallel to said matlongitudinal direction. Regarding the fiber orientation for the zones18, 28, 29, the comments that have been made in conjunction with FIGS. 1through 3 apply. Uncondensed zones 17, 30, 31 are formed between thezones 18, 28, 29, said uncondensed zones preferably accounting for thegreater part of the volume of the damping material 11. In these zones,for example in zone 29, again one or more interstices 27 may be formed.For example, such an interstice 27 extends like a longitudinal channelparallel to the adjacent condensed zones 18, 28.

In the damping material 11, the distances between the parallel,strip-shaped condensed zones 18, 28, 29 has been selected so as to beirregular. FIG. 4 illustrates three such distances L1, L2, L3.Preferably, the distances are not equal. Ideally, none of the distancesL1, L2, L3, etc. is identical. The widths of the zones 18, 28, 29 arepreferably the same among each other.

The damping material 11 in accordance with FIG. 4 can be produced in anapparatus in accordance with FIG. 2 in that a mat 12 of a non-wovenfibrous material is passed through the processing station 22. The fibersare loosely layered in predominantly horizontal orientation and arestacked in a specific height h. The width of the mat 12 is random. Forpractical purposes, these widths are between 50 cm and 5 meters.Preferably, the mat 12 is obtained by continuous production and can thusbe adjusted as desired by cutting.

FIG. 5 shows a damping material 11 representing a multi-layer assembly.As illustrated, the material comprises two or also more layers 32, 33,of which at least one, preferably however more or all of them, have oneor more condensed zones 34, 35, 36, 37. Considering the composition ofthe layer 32, all the explanations provided regarding the exemplaryembodiment of FIG. 4 apply. Likewise applicable to the layer 33 are theexplanations provided in conjunction with FIG. 4. Consequently, asexplained in conjunction with FIG. 4, the layers 32, 33 may be firstprovided separately and then be superimposed. In doing so, the condensedzones 34,35 of the upper layer 32 may be oriented parallel to thecondensed zones 36, 37 of the lower layer 33, whereby they, preferably,need not be moved in a registered manner. As a result of this, thedistances of the condensed zones 34, 35 of the upper layer 32 may bedifferent from the distances between the condensed zones 36, 37 of thelower layer 33. The layers 32, 33 may be different regarding the numberand position of the condensed zones 34 through 37.

As many such layers as are desired may be placed on each other. Ifneeded, layers without condensed zones may be interposed. The cohesionof the layers 32, 33, as well as all potentially additionally presentlayers can be created by continuously condensed zones 38 that extendparallel to the other condensed zones 34 through 37, or also in adirection transverse to them. The continuous condensed zones 38 arepreferably produced in that the individual layers 32, 33 are placed ontop of each other. For example, they can be produced by condensing withwater jets or by any other mode of condensing as mentioned in thisdocument. Preferably, as illustrated, they are strip-shaped. However, itis also possible to produce continuous condensed zones having a locallylimited contour, said contour being round, oval or rectangular, forexample. In the condensed zone 38, the fibers are transferred from theupper layer 32 into the lower layer 33. Additionally or alternatively,the fibers of the lower layer 33 may have been transferred from thelower layer 33 into the upper layer 32. Again, as in all the othercondensed zones, there is a greater degree of interlooping of fibers inthe condensed zone 38 than in the surrounding material of the first zone17. The condensing or interlooping of fibers in the zone 38 may be thesame as in the zones 34 through 37. However, it is also possible tospecify different degrees of interlooping and condensing for the zones34 through 37 and 38.

As a result of the number and arrangement of condensed zones 34 through37 and 38 and their degree of condensation, as well as the number oflayers 32, 33, etc., it is possible to adjust the damping properties ofthe damping material 11 within wide limits as desired.

The damping material 11 in accordance with FIG. 5 may haveinterstices—like the already described interstice 27—within the layers32, 33. In addition, interstices extending toward the respectively otherlayer are formed on the condensed zones 34, 35 as well as 36, 37. FIG. 5shows such an interstice 39 between the condensed zone 35 and the layer33. Such interstices can improve sound-damping properties. The distancesof the condensed zones 34, 35, 36, 37, 38 from each other, as well asthe geometric distances relative to the interstices 27, 39, arepreferably within the range of half the wavelength of the sound waves tobe attenuated or a multiple of half the wavelength. If, for example, inparticular a frequency of 200 Hz is to be attenuated, the distances maybe in the range of 85 cm. If the focus of the damping effect is to be at2000 Hz, it is advantageous to specify the distances in the range of 8.5cm. A broader frequency spectrum can be covered by varying thesedistances.

FIG. 6 shows another embodiment of the damping material 11 in accordancewith the invention, said damping material having at least two layers 32,33. In this case, the layers 32, 33 are oriented transversely withrespect to each other. While the condensed zones 36, 37 of the lowerlayer 33 extend in a first direction, the condensed zones of the upperlayer (zone 34) are oriented transversely with respect thereto. Theconnecting condensed zone 38 may extend parallel to the zone 34,transversely with respect to the zones 36, 37, or in a separatedifferent direction. Due to the mutual crossing of both the condensedzones 34 and 36, as well as 37, additional interstices are formed in thedamping material 11, said interstices being capable of affecting thesound-damping effect in a positive manner. In the layers 32, 33, thefibers in the uncondensed zones 17 may be oriented parallel to eachother or also crossed with respect to each other.

In each of the presented embodiments representing a multi-layerassembly, the damping properties can be additionally influenced in thatthe geometric configuration of the obtained interstices and theirrelative distances are adjusted to the frequency that is to beattenuated.

Furthermore, the damping properties can be adjusted in that the layers32, 33 and, optionally, additional layers are made of different groundfiber materials, so that different mass densities result in view of thespatial volume segment. In addition, it is possible to vary the densityof the non-woven fibrous web in a direction transverse to the matlongitudinal direction 21.

FIG. 7 is a schematic illustration of the condensing process by means ofthe water jet method. Again, the mat 12 has been produced with a knownmethod such as carding, optionally also by cross-laying or by producinga spunbonded fabric. This mat 12 moves in the direction of the matlongitudinal direction 21 under a nozzle bar 49 of a water-jetcondensing system, said nozzle bar being known per se. The nozzle bar 49may be part of one of the members 23, 24 shown in FIG. 2. Again, thenozzle bar 49 comprises at least one, preferably however more, nozzleclusters 40, 41, 42, 43 and, optionally, even more such nozzle clusters.Each of the nozzle clusters 40 through 43 that are schematicallysymbolized by circles in FIG. 7 may be individually formed by a group ofsmaller nozzle orifices that are arranged linearly or in an array. Thedistances between these nozzle clusters L1, L2, L3 are preferably notidentical to one another.

Each nozzle cluster 40 through 43 produces a bundle 44, 45, 46, 47 ofwater jets that impinge on the surface of the mat 12 and penetrate thematerial of the mat. The impinging water jet bundles 44 through 47 causea fluidizing of the fibers in the mat 12 and a reorientation, as well asthe interlooping of said fibers. This is also accompanied by acondensing of the material of the mat 12 so that, as the workprogresses, the strip-shaped condensed zones 18, 34, 35, 36 are formed.The diameter of the nozzle clusters 40 through 43 and the pressure ofthe water that is applied above the nozzle bar 49 are selected in such amanner that the water jet bundles 44 through 47 fluidize said fibers butdo not cause a separation or even a destruction of the fibers. In doingso, it is important that, between the individual water jet bundles 44through 47, there be at least one interstice in which no condensing ofthe mat 12 occurs so that here—in order to form zone 17—there is noincreased density of the non-woven fabric. A condensing of the mat 12occurs only in the region of action of the water jet bundles 44 through47. Furthermore, measures may be taken to temporarily interruptindividual water jet bundles 44 through 47, for example the water jetbundle 45. This may be accomplished by means of a baffle that is pushedinto the region of the water jet bundle 45 in order to interrupt thelatter. This means that, with a forward movement of the mat 12 under thenozzle bar 49, a strip-shaped condensed zone is created through theentire height of the mat, said zone being interrupted in matlongitudinal direction 21.

The activation and deactivation of the condensing effect cannot only beachieved by temporarily covering the individual nozzle cluster 40through 43 but also in that the entire nozzle bar, for example of themembers 23, 24, etc., is activated and deactivated.

The method is suitable, in particular, for mats 12 of polyester fibers.However, it is not restricted to a specific fiber material. In addition,the manufacture of the damping material 11 is possible not only by waterjet condensing but also by other methods for locally condensing the mat12. Methods using mechanical needling or thermal condensing can be used.Essential is that zones exhibiting varying spatial densities be producedin the damping material 11 in a targeted manner.

A damping material 11 in accordance with the invention consists of aground material that is composed of fibers that are in loose connectionwith each other. For example, the fibers are minimally interlooped witheach other or also glued to each other. This ground material iscondensed in some areas in that the fibers are reoriented or interloopedwith each other to a greater degree or glued to each other.Consequently, zones 17 and 18 of different densities are formed, thusmaking it possible to increase and adjust, as desired, the sound-dampingeffect of the damping material.

It will be appreciated that the above description of the presentinvention is susceptible to various modifications, changes andmodifications, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

List of Reference Numerials: 10 Random-fiber non-woven body 11 Dampingmaterial 12 Mat 13, 14, 15, 16, 25, 26 Fiber 17 Zone with minimal fiberinterlooping 18 Zone with increased fiber interlooping 19 Upper side 20Underside 21 Mat longitudinal direction 22 Processing station 23, 24Member 27, 39 Interstice 28, 29, 34, 35, 36, 37 Linear zone withincreased fiber interlooping 30, 31 Linear zone with minimal fiberinterlooping 32 Upper layer 33 Lower layer 38 Condensed zone traversingthe layers 32, 33 40 First nozzle cluster 41 Second nozzle cluster 42Third nozzle cluster 43 Forth nozzle cluster 44 First water jet bundle45 Second water jet bundle 46 Third water jet bundle 47 Fourth water jetbundle 49 Nozzle bar

1. Acoustic damping material (11) consisting of a random-fiber non-wovenbody (10) that is made of interlooped fibers (13, 14, 15, 16) and has atleast two spatial zones (17, 18, 28, 29) displaying different degrees offiber interlooping.
 2. Damping material as in claim 1, characterized inthat the two zones (17, 18, 28, 29) displaying different degrees offiber interlooping have different fiber densities.
 3. Damping materialas in claim 1, characterized in that the spatial zones (17, 18, 28, 29)are arranged in an irregular pattern.
 4. Damping material as in claim 1,characterized in that the fibers in the zones (17) displaying a lowerdegree of fiber interlooping are oriented predominantly in one plane,while, in the zones (18, 28, 29) displaying a greater degree ofinterlooping, a larger proportion of said fibers is oriented in adirection perpendicular to said plane.
 5. Damping material as in claim1, characterized in that the zones (18, 28, 29) displaying the greaterdegree of fiber interlooping have the form of strip-shaped regions. 6.Damping material as in claim 5, characterized in that the zones (18, 28,29) are arranged at different distances from each other and parallel toeach other.
 7. Damping material as in claim 1, characterized in that therandom-fiber non-woven body (10) comprises several layers (32, 33) thatare made of interlooped fibers (25, 26), whereby at least one layer (32)of said layers has the zones (17, 34, 35) displaying different degree offiber interlooping.
 8. Damping material as in claim 7, characterized inthat at least two of said layers (32, 33) have zones (17, 34, 35, 36,37) displaying different degrees of fiber interlooping, said zones beingarranged differently.
 9. Damping material as in claim 8, characterizedin that the zones (17, 34, 35, 36, 37) of the layers (32, 33) arestrip-shaped and are superimposed in a manner so as to cross each other.10. Damping material as in claim 1, characterized in that the fiber body(10) contains interstices (27, 39) that are free of fibers or have afiber density that is considerably reduced compared to the surroundingfiber body (10).